1. Field of the Invention
The present invention relates generally to a lift for a vehicle, and in particular to a roll stop for the lift.
2. Description of Related Art
Lift systems are used in conjunction with vehicles to transport wheelchairs, persons, and cargo, etc. Some of these lift systems are self supporting and can be rolled or otherwise pushed against a vehicle opening. Other such systems are appended to the bottom of a vehicle chassis while others are supported at or about the sidewall of the vehicle proximate the vehicle opening. The lift systems are configured to raise and lower a wheelchair, a passenger, or cargo to and from the vehicles using a platform. The platform may be raised or lowered between the ground and the vehicle using, for example, hydraulic or electrical, actuators that provide the lifting force.
Typical lift systems are provided with certain general design components dictated principally by the need to capture and lift the wheelchair-bound passenger or cargo in a safe fashion, as well as to enable the systems to fold or be made unobtrusive when not in use, such as when the vehicle is moving.
A common lift design is a parallelogram design that uses two sets of lift arms arranged in a parallelogram or near-parallelogram arrangement on either side of the platform. Using the parallelogram keeps the lift platform in a horizontal orientation, i.e., parallel to the ground level, when the lift platform is being moved up and down.
This lift design also provides for a storage orientation enabling the platform to swing in a ninety degree arc to assume a substantially vertical orientation once the passenger or cargo is on board to enable the vehicle to proceed in a normal fashion.
The lift systems typically also include inboard and outboard roll stops on front and rear edges of the lift platform to prevent the wheelchair or cargo from inadvertently sliding off the platform during transition, and to act as ramps for loading and unloading when the platform is on the ground or level with the vehicle bed. In a typical configuration, the outboard roll stop rotates from a substantially vertical orientation to a substantially horizontal orientation acting as a ramp at ground level to enable a wheelchair to be rolled onto the platform. At the same time, the inward roll stop is at a substantially vertical orientation to prevent the wheelchair from inadvertently traveling off of the platform at its inner edge.
As the hydraulics are actuated resulting in lifting of the platform, both the outboard and inboard roll stops maintain a substantially vertical orientation, thus capturing the wheelchair or cargo on the platform. Once the platform reaches the vehicle entrance, the outboard roll stop maintains its substantially vertical orientation, while the inboard roll stop travels in an arc to act as a bridge plate between the platform and the vehicle bed.
Various mechanisms have been provided to enable the inboard roll stop to move from a blocking (vertical) orientation to a loading (horizontal) orientation simultaneously as the wheelchair reaches the vehicle opening without human intervention. Likewise, as the platform is lowered from the vehicle opening towards ground level, the roll stop actuating mechanisms can simultaneously move the inboard roll stop to a blocking orientation without input from the operator.